The art of wind-powered prime movers which operate to put the work energy of wind to useful work is extremely old and highly developed.
Apart from wings and sails, there are two common or basic classes of wind-powered prime movers. The first and most familiar class of wind-powered prime movers include and are characterized by rotatable propellers or fans, the rotative axes of which are substantially parallel with the direction of the movement of the air or wind relative thereto and which include pluralities of elongate, circumferentially spaced substantially radially extending blades or vanes which extend outward from the rotative axes of the propellers or fans on radial planes which are substantially normal to the direction of movement of air. The blades or vanes are pitched and/or aerodynamically formed so that the impingement and movement of wind or moving air upon and about them causes the propellers or fans to rotate. The second and also quite familiar class of wind-powered prime movers include rotors, the rotative axes of which are substantially normal to the direction of the movement of air and which include and are characterized by pluralities of circumferentially spaced elongate vanes projecting and/or spaced radially outward from and which extend substantially parallel with the rotative axes of the rotors and which are pitched and/or aerodynamically formed so that wind or air moving by the rotors and across the vanes causes the rotors to rotate.
While the second noted class of wind-powered prime movers, which are characterized by rotors rather than by propellers or fans, have certain characteristics or attributes that appear to make their adoption and use in wind-powered prime movers advantageous, they have, prior to my invention, proven to afford less latitude in design than do propellers and/or fans and have a number of inherent design and/or structural limitations which have led the prior art to avoid the use thereof and to pursue the development and use of propellers or fan type wind-powered prime movers in preference thereto.
In the case of both of the above noted classes of wind-powered prime movers, it is understood and believed that in excess of eighty percent of the energy of the wind or moving air that engages and acts upon the blades and/or vanes of the fans and rotors is not captured and put to use, but is lost as a result of the deflection of the air and the slipping of that air from the tips and/or trailing edges of the blades and vanes. The deflection or changing of the direction of the moving air wastefully consumes much of the energy carried by the air and when the redirected air slips from or leaves the blades and/or vanes, the energy carried by or within that air is lost. Accordingly, under the best circumstances and conditions, wind-powered prime movers are very inefficient.
Another shortcoming found to exist in wind-powered prime movers provided by the prior art resides in the fact that little or no control of the speed of rotation is afforded. Such prime movers, due to their inherent inefficiencies, are commonly designed to turn as freely and as fast as the wind might drive them, whereby as much work energy as possible can be collected by them. As a result of such practices, when there is little wind most wind-powered prime movers turn at speeds below desired or optimum speed and when there is strong wind, they often turn at speeds which are in excess of desired or optimum speed with respect to the various machines or devices they drive or power.
The foregoing is particularly true in the case of those exceedingly large windmill or propellr type wind-powered prime movers which have been constructed in recent years for generating electric power. In the case of those large propeller type electric powered generating wind-powered prime movers, the aerodynamic shape and structural characteristics of the propellers must be established for most effective and efficient operation when worked upon by the mean or average prevailing wind in the areas in which the structures are used. The latitude for design is therefore quite limited. When such structures are acted upon by winds that are notably greater or stronger than the average wind they are designed to be operated by, the strong winds frequently result in overstressing and subjecting the blades to destructive forces which cannot be avoided by feathering the blades and which are greatly increased by braking or otherwise forcibly slowing rotation of the propellers.